Phonograph record molding compositions and records



Patented Jan. 15, 1952 UNITED STATES PATENT OFFICE PHONOGRAPH RECORDMOLDING COMPOSITIONS AND RECORDS Joseph W. Ayers, Easton, Pa., assignorto Agrashell, Inc., a corporation of Delaware No Drawing. ApplicationOctober 18, 1947, Serial No. 780,749

16 Claims.

filler .of .the novel properties hereinafter described,-

in admixture with a plastic or resinous base, and ordinarily also with aplasticizer, a mold lubricant and a stabilizer.

Substantially all commercial phonograph records are molded fromthermoplastic natural or synthetic resin compositions containing one ormore fillers necessary either to control the consistency of thecomposition or to impart wear resistance or sound reproducing fidelityto the records. Because of their hardness and cheapness, inorganicfillers have generally been employed such as ground slate, carbonatesand silica. The addition of such fillers even after the r subjection tofinest mechanical grinding leads to records producing substantialamounts of surface noise when played.

An objectof the present invention is to produce records which thoughcontaining a filler content in equal or larger amounts than recordsmarketed heretofore have superior properties and advantages without theaforementionedand other defects.

Specifically, it is an object of this invention to provide phonographrecord molding compositions having substantial quantities of fillertherein .from which improved phonograph records may be producedhavingreduced surface noise, greater form stability, and greater wearresistance, andat a low cost. Broadly considered, the phonograph moldingcompositions of the present invention are composed of a plastic. orresinous molding compound together with a very finely divided, hard,dense, non-fibrous organic lignocellulose filler containing {at least45% by weight of combined pentosan's, ,hexosans and lignins. Generallyalso a'suitable plasticizer, mold lubricant and stabilizing agent areincluded in the compositions. The diameter of the largest-particles .inthe filler is not more than30 microns and. 90% of the particles have adiameter finer than 25 microns. The filler is also preferably closelyfractionated such that at least-40% .are between wand 25 microns.

The ligno-cellulose fillers maybe further defined as materials derivedfrom natural vegetable shellmaterials including endoearps, asthe shellsof English walnuts, black walnuts, pecans, Brazil nuts, :cocoanuts andthe "like and including the pits of apricots, olives, cherries, dates,peaches and the like and also hard, dense barks ,of a number of treeshaving acell structure which is non-fibrous.

These non abrasive ligno-cellulose materials Q raph records producedtherefrom have surprising inertness and stability against wide ranges oftemperature and humidity conditions.

One of the typical ligno-cellulose fillers made from natural vegetablematerial contemplated by the present invention contains thefollowingcomnonents:

CHEMICAL ANALYSIS Determinations on dry basis Per cent by wt. Nitrogen(N) The inertness and resistance to dissolution of the aboveligno-cellulose filler may be judged from the following table:

SOLUBILITIES Determinations on dry basis Per cent by wt.

Ether p .50 Alcohol (95% for 4 hours). 3.00 Cold water- V 1.00 Hotwater, 2.50 Acetone 3.00 1% sodium hydroxide 14.00 1.0%su1phuric -acid4.54

These novel 'ligno-cellulose filler materials can be successfullysubstituted wholly or in part for any of the ordinary fillers in theusual plastic resinous molding compositions used for phonograph recordproduction. The compositions having a naturalresin base and inparticular shellac have improved properties over'prior conventionalshellac compositions. Vinyl resin compositions containing the saidfillers also have exceptional and valuable properties. Because of theunique properties of these filler materials, large proportions may beemployed successfully. Ordinarily at least 35% by weight may be used andin some compositions as much as may be employed; However, recordsproduced from compositions containing as little as 20% of the fillerhave improved qualities.

Ligno-cellulose fillers exceptionally satisfactory in the compositionsof the present invention are those ground by the process and apparatusdescribed in my copending application, Serial No. 683226 filed July 12,1946 now U. S. Patent No. 2,561,043 and classified by the process of -myapplication Serial No. 683,227 also filed on Julypossessaremarkableresistancezto solvents, water, I 12, 1946 now U. S.Patent No. 2,554,450. A typical weak acidsand weakz'alkaliesand hence:the phon particle distribution in theground walnut shell flour isparticles greater than 30 microns,

the specific surface area approximately 5,000 sq.-

cm. per gram.

Phonograph record molding compositions in which the filler content iscomposed exclusively of the ligno-cellulose products of the characterherein described constitute the preferred embodiments of the presentinvention. However,

compositions containing an inorganic filler in addition to the novelligno-cellulose filler of the present invention possess improvedproperties over compositions containing inorganic fillers orconventional cellulosic fillers or both.

- A preferred composition of the present invention has a high fillercontent consisting of the ligno-cellulose material in a quantity ofabout 50%. volume of molding compositions-containing the conventionalinorganic fillers in equal weights. It is therefore possible to producealmost twice as many records from the compositions of the presentinvention as from such prior compositions. Furthermore, the presentrecords have an advantage in weighing hardly more than onehalf equallyfilled conventional records.

The records produced in accordance with the present invention ascompared with conventional records produce less surface noise, havegreater form stability and have greater wear resistance. These improvedproperties are attributable to the unique properties of theligno-cellulose fillers employed, including their compatibility andbinding power in molded resins, and to the particle size distributionand maximum size of the particles.

It has been determined that at 5,000 cycles, in which range surfacenoise is most disturbing and noticeable to the human ear, a needledeflection of .00005 inch or less will not create a disturbinginterference. It has also been determined that the finely dividedligno-cellulose filler of the present invention in records will notcause needle deflection as great as the indicated amplitude and hencesurface noise caused by needle defiection does not occur, even thoughwearingaway of the shellac or other binding resin due to needle abrasionwill cause the filler particles to protrude and deflect the needle.

This avoidance of objectionable deflection is due not only to smallparticle size of the lignocellulose particles but also to the compliantproperties of the material in the resin base, which properties are notpossessed by inorganic fillers which are generally hard, rigid andabrasive and hence non-compliant.

The invention is brought out in the following Such composition hasalmost double the ligno-cellulose fillers.

4 This formula contains a comparatively low percentage of any one of thehereinbefore' disclosed The composition possesses a specific gravityaround 1.884.

Example 2 Pounds Shellac 26 Congo gum 8 Pine tar resin (vinsol resin) 14Cotton flock 5 Zinc stearate 1% Walnut shell flour filler 60 Carbonblack 4 Total 120 The formula of this example, it will be observed,contains an extender content composed exclusively of the ligno-cellulosefiller, it being presentin the larger proportion of of the total mass.The specific gravity of this compositionis only 1.170.

Example I I Pounds Vinyl resin base 40 Butadiene-acrylonitrile syntheticrubber v lose extender of the present invention.

It will be observed that the filler likewise consists of a singlematerial, that is the ligno-cellu-:

The specific gravity of this composition is 135 Q Q When the formula ofExample 1 is compared with the formula of Example 2, it willbe observedthat 200 pounds of the first composition provides 106.13 volumes whereasthe 120 pounds of'the second formula makes up to 95.67 volumes. Althoughthere is a difference of pounds in. the total weights of the twocompositions, there are nearly as many volumes present in the secondcomposition as in the first composition. This means that almost as" manyrecords can be pro duced from the second composition weighing pounds asfrom the first composition weighing 200 pounds. A record prepared fromthe second composition will weight only 63% as much as the record of thesame size and thickness prepared from the first composition.

It should be understood that the ingredients hereinbefore set out aregiven merely by way of example and that compositions containing: otherconventional or known materials capable of serving the same purposes arealso contemplated. Other plasticizers which may be employed includephthalic esters, chlorinated diphenyl derivatives, tricresylderivatives. halo: genated naphthalene derivatives, glycol esters' andthe like. Other stabilizers are for example, calcium carbonate, leadcarbonate and lead titanate. Other wax lubricants are montan andcandelilla waxes. As an antioxidant there may" be mentionedphenyl-beta-naphthylamine. As a preferred vinyl resin base there may'bementioned a vinyl chloride-vinyl acetate resinin the proportion of 70 to30 parts by weight.

The organic fillers of the present invention are so fine in texture thatthe consistency of duced there'from' a minimum :of surface noise Thefilled rcompositions over the entire range. v s are economical :bo'thincos't oi raw materials and cost of compounding. They-readily'lendcthemselves to processing such as'to workingppressing and blanking.The records produced from such compositions have excellentcharacteristics with respect to both fidelity of reproduction and lengthof playinglife.

The compositions of the invention .may be compounded on conventionalprocessing equip ment. Mixing times and temperatures in the same rangeas now used withother conventionalcompositions may be employed. :Incompound midterm ing the vinyl resin base compositions, the =individualcomponents .are ifirst weighted -'-out."an'd after preferably beingvmixed dry iior a period or a'zfewminu-tes, theyv arenext placed in aBanbury or similar type mixer or upon diflerential rolls.-

The composition is then worked for several min-Q; 1'- utes until thedispersion of the extender used -1 is complete, the temperature employedsuitably being in the neighborhood of 270 F. After being cut a number oftimes with a doctor blade, the

manner.

stock is formed into biscuits in conventional In the molding or pressingoperation the biscuits are suitably heated to 210 F. or

above, and pressure of from 1500 to 4000 pounds per square inch isapplied, depending upon the type and size of record being pressed. Steamheating for a period of seven seconds to a stamper temperature of 270 F.is usually sufficient,

. .35 after which cool water is applied to the die for thirty seconds ormore, thereby, making the total pressing cycle of thirty-seven secondsor more, depending upon the temperature of the cooling water used.Because the composition is highly loaded with the ligno-celluloseextender, air bubbles are not entrapped in the pressed material andhence the percentage of imperfect and rejected records" pressed is muchless than when ordinary Vinylite compositions are pressed. The rippledflash from" the record can be removed easily by breaking.

it 011 by hand, which advantage is in strong contrast to the tough,horny Vinylite fiashre quiring cutting or dieing. The scrap and trim jmings from the pressing operation of the present compositions may besuitably reground on disintegrating mills commonly used to processshellac scrap. The pre-heating required and other problems encounteredin the recovery of- Vinylite scrap are eliminated.

It should be understood that the presentsi'n-f vention is not limited tothe specific examples of materials or proportions herein given, .but

that it extends to all equivalent materials and variations which willoccur to those skilledzgin'; the art upon consideration of the scope of"the" of which are not more than 30 microns in diam-j eter and 90% ofwhich are finer than 25 microns." 2. A filled, thermoplastic phonographrecord} molding composition the filler content of which consists of afinely divided, hard, ligno-cellulose extender containing at least ofcombined pentosans, hexosansiand lignins, the 138113161854 0! theJfilla' being not more than 30 microns .in diameter and of which arefiner than 25 microns.

53. A thermoplastic phonograph record, molding composition havingtherein from 20 to 55% of "an extender composed of'fla finely divided,

hard, -ligno-.'cellulose filler containing iatqleast 45% "of combinedpentosans, hexosans and Jig-- nins, the particles of the filler beingnot more than 30 microns in diameter and 90% pi which are .fine'r than'25 .microns.v I

4. .A .filled thermoplastic phonographrecord mol'ding'composition, thefiller content :'of which amounts'to 20-60% of thecomposition and'comsistscof a finely divided, hard, lignoecellulose tender containing atleast 45% of combinedpentosa'ns, hexosans. and lignins, the particlesofthe filler being not more than 30 microns in -diameter :and 90% of whichare finer than 25 microns. p 5. A thermoplastic phonograph recordmolding composition having therein an extender composed of a finelydivided, nut shell material containing at least 45% of pentosans,hexosans and lignins, the particles of which are not more than 30microns in diameter and 90% of which are finer than 25 microns.

6. A filled, thermoplastic phonograph record molding composition, thefiller content of which consists of finely divided, vegetable materialcontaining at least 45% of pentosans, hexosans and lignins, theparticles of which are not more than 30 microns in diameter and 90% ofwhich are finer than 25 microns.

'7. A thermoplastic phonograph record molding composition having thereinan extender composed of a finely divided, ligno-cellulose fillercontaining at least 45% of combined pentosans, hexosans and lignins, theparticles of the filler being not more than 30 microns in diameter and90% of which are finer than 25 mlcrons, 30% or more of which particlesare between 10 and 25 microns.

8. A thermoplastic phonograph record molding composition having thereinan extender composed of finely divided, walnut shell flour, theparticles of which are not more than 30 microns in diameter and 90% ofwhich are finer than 25 microns.

9. A filled, thermoplastic phonograph record, molding composition, thefiller content of which consists of finely divided, Walnut shell flour,the

particles of which are not more than 30 microns in diameter and 90% ofwhich are finer than 25 microns.

10. A thermoplastic phonograph record, molding composition havingtherein from 20 to 60% of finely divided walnut shell flour, theparticles of which are not more than 30 microns in diameter and 90% ofwhich are finer than 25 microns.

11. A thermoplastic phonograph record having at least one reproducingsurface composed of a resin base and a finely divided, hard,lignocellulose filler containing at least 45% of combined pentosans,hexosans and lignins, the particles of which are not more than 30microns in diameter and 90% of which are finer than 25 microns.

12. A thermoplastic resin base phonograph record, the filler content ofwhich consists of a finely divided, hard, ligno-cellulose extendercontaining at least 45% of combined pentosans, hexosans and lignins, theparticles of said ex- 7 tender being not more than 30 microns indiameter and 90% of which are finer than 25 microns.

13. A thermoplastic resin base phonograph record containing from 20 to60% of a finely divided, hard, ligno-cellulose filler containing atleast 45% of combined pentosans, hexosans and lignins, the particles ofsaidfiller being not more than 30 microns in diameter and 90% of whichare finer than 25 microns.

5 14. A phonograph record composed of a thermoplastic resin base andfrom 50-60% of a finely divided filler consisting of a vegetable she11material containing at least 45% of pentosans, hexosans and lignins, theparticles of which are not more than '30 microns in diameter and 90% ofwhich are finer than 25 microns.

15. A phonograph record composed of a thermoplastic resin base and "afiller composed. of hard, dense, fruit shell material the particles ofwhich are not more than 30 microns in di- REFERENCES CITED The followingreferences are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,006,378 "Whyte et al. July 2,1935 2,307,180 Yngve Jan. 5, 1943 2,319,182 Van der Pyl May 11, 19432,343,247 Simons Mar. 7, 1944 2,412,599 ZBuell Dec. 17, 1946

1. A THERMOPLASTIC PHONOGRAPH RECORD MOLDING COMPOSITION HAVING THEREINAN EXTENDER COMPOSED OF A FINELY DIVIDED, HARD, LIGNO-CELLULOSE FILLERCONTAINING AT LEAST 45% OF COMBINED PENTOSANS, HEXOSANS AND LIGNINS THEPARTICLES OF WHICH ARE NOT MORE THAN 30 MICRONS IN DIAMETER AND 90% OFWHICH ARE FINER THAN 25 MICRONS.